US2772669A - Engine pull starter - Google Patents

Description

Dem 1956 Q w. E. ARMSTRONG 2,772,669

ENGINE PULL STARTER Filed Sept. 8. 1953 3 Sheets-Sheet 1 s a s lg, '95 I I\ 1/ I 42 I7,

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AT TORNEY Dec. 4, 1956 w. E. ARMSTRONG ENGINE PULL STARTER Filed Sept. 8. 1953 Dec. 4, 1956 v w. E. ARMSTRONG 2,77

ENGINE PULL. STARTER Filed Sept. 8. 1953 I 3 Sheets-Sheet 3 INVENTOR AT TORNEY United States Patent ENGINE PULL STARTER Werner E. Armstrong, Milwaukee, Wis., assignor, by

mesue assignments, to Fairbanks, Morse & Co., Clucago, 111., a corporation of Illinois Application September 8, 1953, Serial No. 378,765

Claims. (Cl. 123-185) This invention relates to manually operated devices called pull starters for rotating the crankshaft of an internal combustion engine through self-rewinding, wrapped cord means including releasable means engageable with a part attached to the crankshaft of the engine, which means is released by the motion of the crankshaft when the engine starts, and it resides in an improved form of such apparatus in which a distributed contact expandable traction means is initially engaged with a smooth external drum through a movable but frictionally restrained camming device activated by the applied cranking torque, the camming action being released by the forward motion of the engine when started.

Self-rewinding, manual, internal combustion engine, starting apparatus is in wide use. In some forms such apparatus includes a unidirectionally engaging mechanism comprising ratchet means engageable in a limited number of angularly spaced positions. With such apparatus, engagement of parts with wearing impact usually occurs because of the delay in engagement after initiation of the cranking pull. Other apparatus employs a hindering member engaged under the influence of gravity and disengaged by centrifugal action when the engine starts. Close concentricity of parts is required for proper performance of such devices and spurious wear inducing engagements occur in the final stages of slowing down of the engine when stopped. Other starting devices are dependent upon wrapping friction established by contracting elements which require considerable cord motion for engagement and which are easily disturbed in adjustment and undesirably sensitive to unwanted lubricant invasion.

It is an object of this invention to provide a rewind pull starter of the class above noted in which engagement for cranking occurs in the first very small travel of the starter rope, to preclude impact damage to the starter parts if the starter rope is jerked.

It is another object of this invention to provide a pull starter of the rewind type in which engagement of the starter need not be limited to an integral number of discrete angularly spaced engaging positions, but one in which engagement is or may be ordinarily completed in the position of first contact of the parts.

Another object of this invention is to provide a starter in which disengagement upon starting of the engine is certain and prompt.

Another object of this invention is to provide a starter which may be easily installed and which will function as intended even though a considerable lack of concentricity of parts is permitted.

Another object of this invention is to provide a pull starter wherein the retrieving drum is mounted on a stationary spindle extending into a hollow cup on the crankshaft of the engine, which cup houses outwardly acting traction means and friction restraining means for causing initial engagement of said traction means with the inside of said drum.

Another object of this invention is to provide a starter in which the engageable releasable parts transmit the "ice cranking torque by metallic adhesion by providing for high unit pressures of engagement, nevertheless, within the proportional limits of the materials to prevent destructive wear, so that regardless of penetration of adventitious 'oil film establishment of said torque transmitting metallic adhesion will be ensured.

Another object of this invention is to provide a starter promptly engageable in all positions and nevertheless capable of functioning properly in spite of an invasion of unwanted lubricant.

The foregoing and other objects and advantages of this invention will appear from the description which follows, which is set forth with references to the accompanying drawings forming a part hereof, and in which there is shown by way of illustration and not of limitation one form in which the starter of this invention may be embodied.

In the drawings:

Fig. 1 is a side view in elevation of a starter constructed in accordance with this invention, shown mounted on an internal combustion engine diagrammatically shown in outline only,

Fig. 2 is an enlarged bottom plan view in section of the starter shown in Fig. 1 a part only of the engine being shown in fragmentary form,

Fig. 3 is an enlarged front view in elevation with parts broken away and in section of the starter shown in Fig. 1,

Fig. 4 is a detailed front view in section of the outwardly acting clutch parts of the starter shown in Fig. 1 the parts being in the position occupied when the starter is idle,

Fig. 5 is a detailed front view in elevation and in section of the parts shown in Fig. 4 after the starter cord has been pulled slightly causing initial contact of the clutch parts,

Fig. 6 is a detailed front view in elevation and in section of the parts shown in Figs. 4 and 5 after the starter cord has been pulled far enough to bring the clutch into full engagement, and

Fig. 7 is an exploded view in side elevation of the several parts of the clutch shown in Fig. l excluding certain parts for clarity.

The form of the starter of this invention, shown in the drawings, is adapted to be attached to the flywheel housing 2 of an air-cooled engine 1 in which a flywheel fan, not shown, provides cooling air drawn through a central opening 3 in the flywheel housing 2. A perforated collar 4 for admission of cooling air is received in a recess provided therefore in an open sided flanged mounting ring 5 secured as shown to the flywheel housing 2 by means of cap screws 6.

The flanged ring 5 furnishes a seat against which a cover 7 for the driving parts of the starter is secured by screws 8. The cover 7 provides a rigid support for a centrally located stationary shaft 9 which is aligned with the axis of flywheel 1i) and crankshaft not shown. The shaft 9, as shown, is carried as an insert cast in place, with the aid of knurling 11 in the die cast cover 7, but any suitable rigid assembly which will hold the shaft 9 stationary and aligned with the crankshaft may be employed. To facilitate alignment during assembly a loose fitting centering pin 12 extending into the bore provided therefore and not shown in the end of crankshaft 13 and into a similar central bore in the end of stationary shaft 9 may be provided. Once properly aligned assembly has been made and the starter has been secured with the cap screws 6 the pin 12 performs no further function and therefore may be made of a material which will quickly wear away without damage to the other parts.

The cover 7 is notched as indicated at 14 in-Fig. 3 and the base of the notch is slotted to provide an opening 15 through which a starting cord 16 may enter the cover 7 wound in several'turns as shown in a slot provided there} fore in a starting pulley 17 rotatably mounted'on the stationary shaft 9. The central part of thegroove which receives the starting cord 16 opens into a laterally facing channel 13 in the pulley 17 so that the end of the cord 16 may be brought out at this point and clamped by means of a staple 19 disposed in a gap provided therefor in the collar 20 which provides one wall of the channel 18.

When at rest the starting cord 16 is wound on the starting pulley 17 within the groove provided therefor as shown and when displaced from'this position is rewound by a spiral flat spring 21 secured to the pulley 17 by means of thehooked end 22 engaged with the collar 20 at a gap therein opposite the gap occupied by the staple 19 and passing from therein several'turns to an anchorage with the post 23 secured to the cover 7.

Extending laterally from the side of the pulley 17 opposite the collar 2a is a transversely slotted boss 24 flattened on the faces adjacent the ends of the transverse slot.

Stationary shaft 9 is provided with a reduced end por tion 25 which extends into the slot in the boss 24,which reduced end portion is flattened on diametrically opposed faces. Mounted upon the end portion 25 of the 'sha'ft9 for rotational movement with respect thereto and extending into the slot in the boss 24 is a'frictionally controlled shoe retainer 26 having hook ends 27-27 for holding shoe retaining springs 28-28 in assembled relation to the remaining parts. The shoe retainer 26 is formed with fiat side faces in facing frictional relationship to a pair of friction washers 29-29 backed in turn by retaining washers 30-30. The washers 29-29 and 30-30 have flattened circular openings therein closely corresponding with the cross sectional configuration of the end portion 25 of shaft 9 so that these washers, while free to move endwise, are held securely against rotation on the stationary shaft 9. Bearing against the outer washer 30 is a friction maintaining spring 31 held in place by retaining washer 32 and snap ring 33 which engages the groove 34 in the end of shaft 9.

Loosely surrounding the shoe retaining ends 27-2 7 of the shoe retainer 26 is a pair of torque transmitting shoes 35-35 having outwardly bent trailing end portions 36-36 and outwardly bent leading end portions 37-37. Springs 28-28 bearing against Washers 38-38 act to position the shoes 35-35 as shown in Fig. 4 whenever the pulley 17 is permitted to turn in the rewinding direction that is to say opposite to that indicated by the arrow in Fig. 3. To ensure the return motion positioning referred to the shoe retainer 26 is provided with a pair of shoul ders 39-39 located to engage the sides of the slot in the boss 24 when the ends 27-27 are approximately centered with respect tosaid slot.

Mounted upon the crankshaft end 13 by means of the nut 40 and key means not shown is a starting shell 41 which extends laterally to surround the shoes 35-35 and to present thereto an internal cylindrical surface spaced a short distance from the ends 36-36 and 37-37 when the parts are in the return position shown in Fig. 4. The shell '41 may be flanged as indicated at 42 which flange may be interrupted by slots as shown to engage the knotted end of a cord Wound around the external end of the shell 41 if for any reason the engine must be started without the facilities furnished by the starter of this invention. Thus the starter herein described may be removed for repair or for other purposes leaving emergency means for starting the engine at the disposal of the user. Thisis of substantial advantage where engines-areused in remote locations or for military purposes Where unforeseen damage may arise. V

In operation the user may grasp the handleend 43 of the starting cord 16 and draw on it to cause rotation-of the pulley 17 inthe direction indicated by the arrow in,

4 Fig. 3. At the outset of this motion the boss 24 of the pulley 17 advances toward the relationship indicated in Fig. 5. While the shoe retainer 26 restrained by the friction washers 29-29 remains substantially stationary, the shoulders 39-39 depart from their normal contact with the sides of the slot in the boss 24 and the shoes 35-35 slide across the flattened faces of the boss 2 in a trailing direction until the trailing ends 36-36 come in contact with the internal surface of the shell 41. .The ends 36-36 having contacted the shell 41 as described then become points defining centers of rotation of the shoes 35-35 as they swing to bring the leading edges 37-37 into contact with the internal surface of the shell 41 as shown in Fig. 6. Thereafter, further motion of the pulley 17 without corresponding motion of the shell 41 is precluded unless actual sliding between the shoes 35-35 and the shell 41 occurs. Such sliding however normally will not occur since the tractiveforce between the shoes 35-35 and the-shell ll far exceeds the force" required to crank the engine. This tractive force is maintained throughout the several turns of rotation of the'pulley 17 which may be effected by drawing ont-he cord 16.

Upon starting of the engine and its sudden acceleration in the direction of the arrows shown in Figs. 5 and '6, the shoes 35-35 are immediately carried forwardtothe relationship shown inFig. 4 in which released position the parts will remain throughout the rewinding of the cord 16 and thereafter. The tractive force employed during cranking is developed by the corners id-44 of the boss 24 as indicated in Fig. 6 which engage the shoes 35-35 with a carnming action at a point closer to the trailing ends 36-36 than to the leading ends 37-37; The trailing ends 36-36 are thus crowded against the internal surface of the shell 41 with substantial force greater than that exerted by the ends 37-37 and thisv force grows in proportion to the torque applied through the bo'ss2'4. The main contacting end of the shoes 35-35 is therefore at the trailing edge thereof while the leading end of the shoe serves primarily to furnish a fulcrum upon which the maintenance of this force depends The shoes 35-35 thus are preferably constructed to present two definite and determined spaced contacting portions to the shell 41.

It is preferred that the shoes 35-35 be constructed with sharpened or reduced trailing end portions 36-36 in order that theunit pressures of contact-between them and the shell 41 will be high enoughto penetrate any ordinary extraneous lubricant film which may form. The tractive force obtainable in this way is approximately the same whether the internal surface of shell 41 is lubricated or not.

The pointed or nearly pointed trailing ends 36-36 preferably are 'so' formed that the forward faces thereof are disposed nearly at right angles to the internal surface of "the shell 41, the opposite'surface being at approximatelythirty degrees with respect to the in'ternal'surface of the shell 41. Considerable variation in theseangles may, however, be employed-Without adversely effecting performance. Where the lubricant film is penetrated traction is accomplished through'metallic adhesion and such can be established without permanentdeformatio'n of either the shell '41 or the shoes 35-35. It-has been found that ther zone within which such adhesion may be obtained without permanent deformation'is 10f suffrcient scope so that theshell 41may be made oflow carbon steel or even of aluminum while the sho'es 55-35 may be madfe of hardened steeel andftheshell 41'will serve throughout thenormal life of the engine towhich it is. attachedwithout perceptible wear of the sort which interferes with proper performance of thestructurea By reason of the construction noted there n mi e umbe of pos t ns o 'ic s gma .1' s 16- .comparativelyi short length of cord '16 need 'bei :withdrawn' 'in order to produce engagement of the "parts.

Engagement therefore occurs without impact stress. In the event ofv backfiring of the engine adhesion forces may be overcome and relieving slipping of the parts can occur. In the course of such an action some metal may be removed from the internal surface of the shell 41 but such will not impair the usefulness of the apparatus.

The use of outwardly acting shoes which frictionally engage the internal surface of a surrounding shell, in order to transmit releasable cranking effort in one direction only, has heretofore been proposed. Such starters, however, have utilized eccentric members or shoes brought into engagement with the shell during cranking either by frictional drag acting through the running crankshaft, or by gravity effects. In either case rubbing parts remain or may remain in contact throughout the :entire running period of the engine which parts soon wear to the point where dependable starter action becomes unlikely. .The engageable starter parts of the apparatus of this invention are, however, completely released upon starting of the engine.

The starter as shown and above described may be re- .assembled for the starting of an engine which rotates in the opposite direction. When this is done, the spring 21 is inverted and the cord 16 rewound in the opposite direction. By reason of the shape of the indentation 14 and slot 15 the cord 16 will emerge without hindrance and the handle 43 will be received in a natural position at right angles to that shown in Fig. 3.

cord pulley rotatably mounted on said pivot, a clutch support secured to said pulley and extending into said shell having at least one clutch shoe seat, a clutch shoe received on and normally urged toward said seat having a contacting trailing end and a contacting leading end adapted to be shifted outwardly into contact with the interior surface of said shell, means activated by rotation of said pulley in the cranking direction cooperatively engaging said shoe to force the contacting ends of the same outwardly into contact with said shell, the contacting portions of the trailing end of said shoe being small in area to impose a high contacting stress per unit of area sufficient to penetrate any lubricant film accidentally adhering to the interior surface of said shell without substantial permanent deformation of said shell.

2. In a pull starter the combination comprising a circular shell attachable to the crankshaft of an engine to be started, a stationary mounting including a pivot in alignment with said shell, a spring-retrieved wrapped-cord pulley rotatably mounted on said pivot, a clutch support secured to said pulley and extending into said shell having transverse clutch shoe seats, a clutch shoe received on and spring urged toward each of said seats said clutch shoes having contacting trailing ends and contacting leading ends adapted to be shifted outwardly into contact with the interior surface of said shell, friction means engaging the pivot on said mounting activated by rotation of said pulley in the starting direction cooperatively engaging said shoes to force the contacting ends of the same outwardly into contact with said shell, the contacting portions of I ment with said shell, a spring-retrieved wrapped-cord pulley rotatably mounted on said pivot, a clutch support secured to said pulley and extending into said shell having at least one clutch shoe seat, a clutch shoe received on and normally urged toward said seat having a contacting trailing end and a contacting leading end adapted to be shifted outwardly into contact with the interior surface of said shell, said seat being short in relation to said shoe so that the trailing end of said shoe overhangs the trailing end of said seat, means activated by rotation of said pulley in the starting direction cooperatively engaging said shoe to force the contacting ends of the same outwardly into contact with said shell with the trailing end of said seat in fulcrumed engagement with said shoe to apply engaging pressure thereto in proportion to the torque exerted by said pulley, the contacting portions of the trailing end of said shoe being small in area to impose a high contacting stress per unit of area sufficient to penetrate lubricant film accidentally adhering to the interior surface of said shell without substantial permanent deformation of said shell.

4. In a pull starter the combination comprising a stationary pivot support adapted to be secured to an engine to be started in alignment with a rotatable part thereof, a hollow circular shell in alignment with said pivot secured to said rotatable part of said engine, a starting pulley rotatably mounted on said stationary pivot, a starting cord in wrapped engagement with said pulley, a retrieving spring resiliently engaging said pulley to urge the same in that direction which will restore the wrap of said starting cord when displaced, outwardly movable clutch members carried by said pulley disposed within said shell, resilient means for normally maintaining said clutch members out of contact with said shell, a stationary friction member non-rotatably held with respect to said stationary pivot, and a movable friction member rotatable by said pulley through a lost motion connection therewith in frictional contact with said stationary friction member cooperatively engaging said clutch members to apply a frictionally induced outward force thereto to cause engagement of the same with said shell when said pulley is rotated by a pull applied to said cord to unwrap the same, and movable to permit said resilient means to apply a releasing force to said clutch members when said pulley is moved in the cord wrapping direction by said retrieving spring.

5. In a clutch for a pull starter having a stationary pivot support adapted to be secured to an engine to be started in alignment with a rotatable part thereof, a hollow circular shell in alignment with said pivot secured to said rotatable part of said engine, a starting pulley rotatably mounted on said stationary pivot, a starting cord in wrapped engagement with said pulley, and a retrieving spring resiliently engaging said pulley to urge the same in that direction which will restore the wrap of said starting cord when displaced; said clutch comprising in combination outwardly movable clutch members carried by said pulley disposed within said shell, resilient means for normally maintaining said expandable clutch means out of contact with said shell, a stationary friction member non-rotatably held with respect to said stationary pivot, a movable friction member connected to said pulley through lost motion means in frictional motion retarding contact with said stationary friction member cooperatively engaging said outwardly movable clutch members to apply a frictionally induced engaging force thereto to cause engagement of the same with said shell when said pulley is rotated by pulling said cord to unwrap the same, and movable to permit said resilient means to apply a releasing force to said clutch members when said pulley is moved in the cord wrapping direction by said retrieving spring, and cam means interposed between said pulley and said clutch members to apply an augmented engaging force thereto when said pulley is moved in the cord unwrapping direction.

7 6. I n a pull starterthe combination comprisinga stationa ypivotsupport adapted to be secured to an engine to befistarted in alignment with a rotatable part thereof, a hollow circular shell in alignment with said pivot secured to said rotatable part of said engine, a starting pulley rotatably mounted on said stationary pivot, a star"- ing cord in wrapped engagement with said pulley, a retrieving spring resiliently engaging said pulley to urge the same in that direction which will restore the wrap of said starting cord when displaced, outwardly movable clutch members carried'by said pulley disposed within saidshell shiftable to and from an engaged position with respectto said shell, a stationary friction member nonro tatably held with respect to said stationary pivot, a

rotatable friction drag member in frictional retarding contact with saidstationary friction member, abutment means secured to' said pulley positioned to engage said rotatable friction drag member to compel rotation thereof notwithstanding said retarding friction'only after substantial relative motion between the same, and clutch shifting means cooperatively engaging said outwardly movable clutch members said movable friction drag means and said pulley to cause engagement'of said outwardly movable clutch members with said shell when relative motion occurs between said pulley and said rotatable friction drag means during rotation of said pulley in the cord unwrapping direction and for applying a releasing force to said outwardly movable clutch members when opposite relative motion occurs.

7. In a pull starter a mounting attachable to an engine to be started, a stationary shaft secured to said mounting in alignment with a rotatable part of said engine, a pulley mounted for rotation on said stationary shaft, a starting cord Wrapped on said pulley to turn the same in starting direction when pulled, a retrieving spring engaging said mounting and pulley to rotate the latter in the wrapping direction when said cord is released, a shell mounted on said rotatable engine part surrounding a portion of said stationary shaft, friction means including a pair of friction discs resiliently urged toward one another non-rotatably mounted on said stationary shaft and a rotatable part disposed between said discs in frictional engagement therewith, means forming a lost motion connection between said pulley and said rotatable friction part, a pair of shoe seats secured to said pulley and received within said shell, a pair of clutch shoes mounted on said seats normally out of' contact with said shell, and means secured to said rotatable friction part and engaging said shoes for compelling said shoes to move outwardly into contact with said shell and to thereafter rotate with said pulley and tocause rotation of said shell when said pulley is rotated.

8. In a clutch a driving member, journal means mounting said driving member for rotation, a rotatable driven member having a circular clutch shoe engaging surface, said driving member providing a clutch shoe seat including a'camming portion, disposed to rotate therewith adjacent the circular surface of said driven member, means rotatable by the driving member and including a clutch shoe having spaced contacting ends, said shoe seating on said seat in disengaged position and being movable therefrom by said camming portion of the seatupon rotation of said drivingmember, to amengag'e'd positibn' relative to said engaging surface ,of saijd driven member with its contacting ends injengagement with said surface, and one of the contacting ends of said shoe'being small in .area to impose a high contacting stress per unit of area sufiicient to penetrate lubricant film accidentally adhering to the engaging surface of said driven member without substantial permanent deformation thereofl.

9. In a clutch a driving member, journal means mounting said driving member for rotation, a non-rotatable drag means secured to said journal means adjacent said driving member, a rotatable driven member having a circular clutch shoe engaging surface, a clutch shoeseat including a camming portion secured to said driving member to rotate therewith adjacent the circular surface of said driven member, a clutch shoe having. a contacting trailing end and a leading end, means normally urging said shoe to a seating position on said seat, said shoe being adapted to be shifted from said seating position to a clutching position having the ends thereof engaging the circular surface of said driven member, means forming a connection between said drag means and said shoe, the last said means and said camming portion cooperating when said driving member is rotated, to effect said shift of the shoe from its said seating position to said clutching position, and the contacting trailing end of said shoe being small in area to impose a contacting stress sufiicient to penetrate lubricant film adhering to the engaging surface of said driven member.

10. In a pull starter a mounting attachable to an engine to be started, a non-rotatable journal secured to said mounting in alignment with a rotatable part of said engine, a pulley mounted for rotation on said journal, a starting cord wrapped on said pulley to turn the same in starting direction when pulled, a retrieving spring engaging said mounting and pulley to rotate the latter in the wrapping direction when said cord is released, driving clutch means mounted on said pulley for rotation therewith and movable to and from released and engaged positions, a driven clutch member mounted on said rotatable engine part adjacent said driving clutch means to be engaged thereby, friction means including a stationary part secured to said journal and a rotatable part in frictional engagement therewith, said rotatable friction part being joined 'to said pulley by a lost motion connection and being in cooperative engagement with said driving clutch means to cause the same to move to engaged position with said driven clutch member upon turning of said pulley in the cranking direction, and resilient releasing means interposed between said driving clutch means and said pulley acting torurge said driving clutch means to released position when said pulley is idle to prevent vibrationally induced false engagement of said driving and driven clutch means.

Kissel May 9, 1944 Johnson et a1. May 20, 1952

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